1. Field of the Invention
The present invention relates to the field of design of electronic circuits, and more specifically to a method and apparatus for reducing power/area requirements to support sleep mode operation when regulators are turned off.
2. Related Art
Regulators generally refer to components which provide constant voltage or current signals (“constant signal”) to other components of a system. The constant voltage or current signals are generally required as input signals for the operation of such other components.
There is a general need to reduce the power consumption requirements in systems. One technique often employed is to make inactive (or disable) the components, which are not required to be operational in the corresponding time durations. At least some of the inactive components are powered down, and the system (or a portion) containing the components is said to be in the ‘sleep mode’.
Another technique employed in conjunction with placing the components in sleep mode, is to turn off the regulators providing the constant signals to the components in sleep mode. By turning off the regulators, the power consumption is further reduced.
One known problem with turning off the regulators is that it may take unacceptably long time to provide the desired constant signal again, soon after it is determined to activate (or bring out of sleep mode) the corresponding components.
One source of such a long time is the presence of a capacitor, generally used to filter any transients in the constant signal, before being provided to the components. The capacitor would need to be charged before the desired level of the signal is provided as input to the components, and the charging may take long duration due to the large capacitor size typically used.
Accordingly, a prior embodiment uses circuits, with each circuit being associated with a corresponding regulator/capacitor combination to maintain the voltage across the corresponding capacitor at a desired level. As a result, the constant signal can be provided soon after it is determined to activate the corresponding components.
One problem with such an approach is that the power and area requirements of the corresponding implementations may be unacceptably high due to the use of such multiple circuits to maintain the voltage levels. Accordingly, what is required is a method and apparatus which reduces power and/or area requirements to support sleep mode operation when regulators are turned off.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.